Query By Example (QBE) — Capabilities and Limitations Which statement about QBE (Query By Example) is accurate in practice?
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AAn official, universal standard exists for QBE across all DBMSs.
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BQBE cannot be used for client/server systems.
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CQBE does not provide a visual query-building environment for programmers.
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DQBE is a visual approach to constructing queries; complete end-to-end applications are not generally built using QBE alone.
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EQBE guarantees better performance than SQL for the same queries.
Answer
Correct Answer: QBE is a visual approach to constructing queries; complete end-to-end applications are not generally built using QBE alone.
Explanation
Introduction:QBE (Query By Example) lets users compose database queries through a tabular or form-based interface instead of writing query text. This question separates realistic capabilities of QBE from common misconceptions and exaggerations.
Given Data / Assumptions:
- QBE is often implemented in tools like Microsoft Access and some ER/BI tools.
- It is meant to simplify query creation for users and analysts.
- QBE is not a complete application framework.
Concept / Approach:We look for the statement that accurately positions QBE as a visual query builder, not an application development platform, and not a universal standard with guaranteed performance advantages.
Step-by-Step Solution:1) Eliminate claims of a universal standard—no single cross-vendor QBE standard exists.2) Eliminate the claim that QBE cannot be used with client/server; it can be used to drive client/server queries.3) Eliminate the statement denying a visual environment; visualization is QBE’s core feature.4) Select the statement acknowledging QBE as a visual query tool, not a full app platform, and not inherently faster than SQL.
Verification / Alternative check:Tools expose QBE-like designers that generate SQL under the hood; full applications still require UI, logic, and deployment frameworks beyond QBE.
Why Other Options Are Wrong:
- Official universal standard: No such global standard.
- Cannot be used for client/server: Incorrect; QBE-generated queries can target client/server DBMSs.
- No visual environment: Contradicts QBE’s essence.
- Guaranteed performance: Performance depends on the resulting SQL and database design, not the query builder UI.
Common Pitfalls:Assuming a visual tool replaces knowledge of schemas or indexing; understanding data structures still matters for effective queries.
Final Answer:QBE is a visual approach to constructing queries; complete end-to-end applications are not generally built using QBE alone.